I want to go to Costa Rica in July, I would be arriving in San Jose and go to tamarindo to surf. Besides hostal, how much would I need to rent a board, food, drinks and traveling? I would like to go for one week or 2. Also is it better to take my board or rent it there?

Looks like boards rent from $20 a day or $120 a week. Spiritair charges $100 each way for boards so not having to carry boards with you is prob the best bet. Locals will know about cheap hostals, food etc.